表面张力测量方法综述

表面张力是流体的一个重要物性数据,本文介绍了几种代表性的表面张力测量方法,包括:毛细上升法、最大气泡压力法、吊环法、滴重法,表面波法.针对各种测量方法的特点和应用范围进行了分析和讨论.     

Surface Levels and Their Contribution to the Surface Tension of Quantum Liquids

We investigate the new type of excitations on a liquid surface, which were proposed in A.M. Dyugaev, P.D. Grigoriev (JETP Lett. 78:466, 2003) to explain the long-standing puzzle of the strong temperature dependence of the surface tension coefficient of liquid helium. These excitations, called surfons, appear because helium atoms have discrete energy level at the liquid surface, being attracted to the surface by the van der Waals force and repulsed at a hard-core interatomic distance. The surfons propagate along the surface and form a two-dimensional gas. The concentration of the surfons increases with temperature. Basing on the simple quantum-mechanical model of the surfon microscopic structure, we estimate the surfon activation energy and effective mass for both helium isotopes. We also calculate the contribution of the surfons to the temperature dependence of the surface tension, taking into account the experimental temperature dependence of the chemical potential of liquid helium. This allows to achieve very high agreement between our theory and experiment on the temperature dependence of surface tension from zero to almost boiling temperature and to determine the contribution of ripplons. This temperature dependence is quadratic in a wide temperature interval for both helium isotopes. The comparison with experiment allows to extract the surfon activation energy and effective mass. The values of these surfon microscopic parameters agree with the values, calculated from the proposed microscopic model of surfon structure.     

A Simple Prediction Method for the Surface Tension of Ionic Liquids as a Function of Temperature

In this study, a simple prediction method for the surface tension of ionic liquids (ILs) as a function of temperature is developed. Based on a database of experimental surface tension values collected from the literature, first a prediction scheme for the surface tension at a reference temperature of 298.15 K using only information on the density, molar mass, and anion type of the IL is suggested. By combination of this approach with the temperature dependence of the density, an extended prediction scheme describing the temperature dependence of the surface tension of ILs is recommended. The optimized prediction model for the surface tension allows for the prediction of about 3500 temperature-dependent experimental surface tension data of 226 different ILs with a standard deviation of about 7 %. In comparison with fluid-specific prediction methods found in the literature, the developed simple empirical prediction model requires only easily accessible parameters and can be applied for ILs with arbitrary cation and anion combinations. Thus, the proposed prediction method seems to be a valuable engineering tool for the quantitative estimation of the surface tension of ILs.     

Development of Maximum Bubble Pressure Method for Surface Tension Measurement of High Viscosity Molten Silicate

A surface tension measurement method based on the maximum bubble pressure (MBP) method was developed in order to precisely determine the surface tension of molten silicates in this study. Specifically, the influence of viscosity on surface tension measurements was quantified, and the criteria for accurate measurement were investigated. It was found that the MBP apparently increased with an increase in viscosity. This was because extra pressure was required for the flowing liquid inside the capillary due to viscous resistance. It was also expected that the extra pressure would decrease by decreasing the fluid velocity. For silicone oil with a viscosity of \(1000\,\hbox {mPa}{\cdot }\hbox {s}\), the error on the MBP could be decreased to +1.7 % by increasing the bubble detachment time to \(300\,\hbox {s}\). However, the error was still over 1 % even when the bubble detachment time was increased to \(600\,\hbox {s}\). Therefore, a true value of the MBP was determined by using a curve-fitting technique with a simple relaxation function, and that was succeeded for silicone oil at \(1000\,\hbox {mPa}{\cdot } \hbox {s}\) of viscosity. Furthermore, for silicone oil with a viscosity as high as \(10\,000\,\hbox {mPa}{\cdot }\hbox {s}\), the apparent MBP approached a true value by interrupting the gas introduction during the pressure rising period and by re-introducing the gas at a slow flow rate. Based on the fundamental investigation at room temperature, the surface tension of the \(\hbox {SiO}_{2}\)–40 \(\hbox {mol}\%\hbox {Na}_{2}\hbox {O}\) and \(\hbox {SiO}_{2}\)–50 \(\hbox {mol}\%\hbox {Na}_{2}\hbox {O}\) melts was determined at a high temperature. The obtained value was slightly lower than the literature values, which might be due to the influence of viscosity on surface tension measurements being removed in this study.     

β因子校正法测定Pb-Cu、Bi-Cu合金表面张力

采用座滴法技术,通过“软件化”的自编 B-A 表和相应的β因子校正法程序,测定了 Pb-Cu,Bi-Cu 合金的表面张力。测定结果表明:Pb-7%wtCu 的元合金在850℃、900℃;Bi-26%Cu 二元合金在850℃的表面张力值分别为408×10~(-3)N·m~(-1)、427×10~(-3)N·m~(-1)以及343×10~(-3)N·m~(-1)。分析和讨论了测量与计算过程中的影响因素。     

Evaluation of the Surface Tension of Liquid Francium

The surface tension of liquid francium is evaluated in a wide temperature range, from its melting point to 800 K, using the correlation between the surface tension of alkali metals (full electronic analogs) and the universal parameter tan in Prikhod'ko's system of unpolarized ionic radii. The credibility of the surface tension data for liquid francium is assessed. The approach used to evaluate the surface tension of Fr is highly reliable because each quantity in the fundamental theoretical relation is determined independently.     

标准粘度液测量结果不确定度分析及评定

本文分析了标准粘度液检测结果测量不确定度的主要来源,介绍了标准粘度液测量不确定度的评定步骤和方法,给出了评定结果。     

Surface Tension Measurements on Industrial Alloys by the Drop-Weight Method

The drop-weight method has been successfully applied to a representative set of industrial alloys (W–Re₂₆, Mo–Re₅₀, Pt–Rh₁₀, Pt–Rh₃₀, Ti–Al₆–V₄, AISI 316 L stainless steel, INCONEL 182 and 600 alloys), with the result that very reproducible surface tension measurements ( /<0.5%) have been established for these materials at the liquidus temperature. This work supports the idea that the simplicity of the drop-weight method should attract much more attention for production control or to provide reference values at the liquidus temperature, although it cannot be used for temperature coefficient measurements of the surface tension.     

表面张力辅助去核法对小鼠卵母细胞的去核研究

论述了一种新的小鼠卵母细胞去核方法─—表面张力辅助去核法 (STA) ,并同时与其他 3种去核方法 (简称A法、B法、C法 )进行比较。STA法是将卵母细胞核在固定管的辅助下 ,借助液体表面张力通过透明带上的破口被挤出。经STA法去核的卵母细胞质体用于电融合介导的小鼠耳成纤维细胞核移植实验 ,结果有76 1%细胞与细胞质体融合形成重组胚 ,85 4%的重组胚形成原核 ,49 4%卵裂形成 2 -细胞     

界面张力仪校准装置示值误差测量值的不确定度评定

本文详细介绍了界面张力仪校准装置示值误差测量值的不确定度评定方法。     

Measurement and Correlation of Surface Tension for Single Aqueous Electrolyte Solutions

In this study, the values of the surface tension for a number of single aqueous electrolyte solutions were measured at various temperatures and electrolyte concentrations using the well-known and computer-aided pendant-drop method. In order to conduct the experimental measurements, a high-pressure IFT-700 apparatus, equipped with a view cell and a data acquisition system, was used. The systems studied in this study were aqueous solutions of KCl, NaCl, CaCl₂, and Na₂SO₄. The pooled standard deviation and the confidence limit of the surface-tension data for a 95 % confidence level were determined to be 0.17 mN · m^?1 and ${\bar{\sigma} \pm 0.19}$ , respectively. It should be noted that while the surface tension for electrolyte solutions increases as the electrolyte concentration increases, it decreases with an increase in temperature as expected. Finally, data reduction was carried out using an empirical equation to show the effect of temperature, electrolyte concentration, and the nature of ionic species on the surface tension for the systems studied.     

一种测定液体表面张力系数的新方法

针对现有的测定液体表面张力系数的方法存在设备昂贵、测定结果容易受各种因素干扰而测试精度不足等问题,提出了一种使用不等内径U型管,采用局部力平衡方法结合拉普拉斯方程,以及MATLAB图像处理和LabVIEW虚拟仪器系统,测定液体表面张力系数的方法。与现有的测定液体表面张力系数的拉脱法相比,该方法具有测试精度高、样品需要量少、测试成本低等特点。     

基于光学非接触测量的车身覆盖件曲面品质综合评价

车身覆盖件曲面品质的纯几何评价准则是曲面品质数字化分析和优化的依据,但是单一的纯几何本构特征准则不能反映产品审美学表观特征的定性指标要求。笔者通过光学非接触测量方法获取车身覆盖件曲面的数字化点进行曲面重构,应用模糊理论建立了车身覆盖件曲面品质分析的综合评价方法。该方法可以为评定车身覆盖件曲面的几何本构特征和审美学表观特征提供依据,为车身设计提供有效的评价尺度。     

表面温度计示值修正值测量结果的不确定度评定

表面温度计示值修正值测量结果的不确定度采用A类、B类方法评定.各个输入量的不确定度分量的来源包括:二等标准热电偶的年不稳定性、电测仪器及冰瓶的测量误差、标准器的使用不确定度、表面温度计测量结果的重复性、检定炉热板温场的不均匀性、及仪表分辨力误差.在建立数学模型的基础上,对标准不确定度进行合成,最后求出扩展不确定度U95=3℃,Veff=50.在符合文中条件的情况下,可根据仪表的分辨力,配用热电偶的类型和测量范围,给出相应的评定结果.     

一种BGA焊锡球表面处理剂及其性能评价

目前国内还鲜见针对芯片封装用焊锡球表面处理剂方面的研究报道.为此,以SnAg3.0Cu0.5合金焊料的球珊阵列封闭(BGA)焊锡球为基础,研制并评价了一种BGA焊锡球表面处理剂.该表面处理剂是由85％～92％(质量分数,下同)的松香、5％～10％的聚乙烯、2％～4％的低熔点蜡以及0.5％～1.0％的活性剂和增塑剂等添加剂组成,再将其按质量份数将1份混合液用80份正己烷稀释而制成.通过对覆膜后BGA锡球的焊接过程、微观组织、空洞情况、黏球情况、抗氧化性以及在焊锡球表面的包裹状态等为评价指标,评价了该表面处理剂的性能.结果 表明:此种表面处理剂的使用能够满足焊锡球的焊点饱满且均匀、焊接性能良好、不黏球、抗氧化膜包覆均匀且抗氧化性能优异等必要条件,能够满足公司内控及BGA焊锡球的客户使用要求.     

测量液体表面张力系数的新方法

介绍了一种利用梅特勒-托利多AB265-S分析天平测量液体表面张力系数的新方法。由实验可以知道，对同一液体，其表面张力系数随着温度的升高而减少，在液体中加入某些活性物质会显著改变液体表面张力，而且随着浓度的增加，表面张力系数减小。     

基于频率法的拉索及吊杆张力测试

拉索及吊杆张力测试结果的正确与否直接关系到桥梁状态的合理确定。基于两端固结梁在轴向拉力作用下横向振动方程,在找出解的规律之后,拟合出轴向拉力与梁的抗弯刚度、长度、线密度及振动频率之间的数值关系,并由此得出适用于拉索和吊杆张力测试计算公式,结果表明该公式具有良好的精度和适用范围。讨论了基于简支梁和弦模型得到的张力测试公式的适用范围,分析表明传统的索力测试公式仅适用于索长细比L/D不小于600时的情形,而本文公式即使L/D小于70亦能给出误差不超过2%的结果。     

高精度表面张力测量装置及其测量不确定度

表面张力是流体重要的基本物性参数之一,是界面现象的重要参数,对于沸腾、凝结换热和多相流动的计算与分析也是必不可少的.研究了基于毛细管上升高差法(DCRM)所建立的混合物表面张力测量的实验方法和实验装置的原理与关键技术,并运用不确定度传递原理建立了DCRM法测量流体表面张力之不确定度的确定方法.     

Measurement of Specific Fracture Energy and Surface Tension of Brittle Materials in Powder Form

Studies of the influence of specimen geometry and size–effect on the K _R –curves and the related fracture parameters were carried out by the authors (Kumar and Barai 2008b). The present paper is a supplementary contribution and reports interesting results related to the effect of the loading condition and size–effect studies on the K _R –curves associated with the cohesive stress distribution for complete fracture process, the double–K fracture parameters, the CTOD–curves and the process zone length using two different loading conditions (i.e., three–point bending test and four–point bending test). The laboratory size specimen with initial–notch length/depth ratios 0.3 and 0.5 are considered in the work. The load–crack opening displacement curves for these loading conditions are obtained using well known version of fictitious crack model.